I'm sorry about posting this here, but I honestly get lost trying to wade through the official bug checking/reporting system to see if it's a known issue...

When Adium is off, the Duck logo disappears from the OS X dock. The space for it is still there, and clicking on the empty space will launch Adium and the "eyes open" Duck will now appear in the Dock. Once I quit Adium, though, the Duck disappears again.

This was not the case in Snow Leopard (10.6.8), but I recently updated to Mavericks (10.9.5) and that's when this bug appeared to me.

Obviously, this is a low-priority bug, but thought it odd enough to mention.

I don't know what may have caused the issue but perhaps try removing and re-adding the dock icon:1. With Adium running, drag the dock icon out from the dock.2. Quit Adium.3. Locate Adium on your Mac (probably in the "Applications" folder) and drag the app to the dock.

David Munch wrote:Right click the app in the Dock, and select Preferences --> Keep in Dock.

It's already a permanent part of my Dock. My wife gets the same thing on her Mac at work. No Duck in the Dock when the app is off. Just a big open space where it should be. The system knows it's there...When you mouse over the blank space, it says Adium, and clicking the blank space launches Adium.